The facts about pest insects and their types

T Many insects are considered pests by humans. Insects commonly regarded as pests include those that are

  • Parasitic e.g. lice, bed bugs,
  • Transmit diseases e.g.mosquitoes, flies,
  • Damage structures e.g. termites,
  • Destroy agricultural goods e.g. locusts, weevils

Insects are considered as pests for a variety of reasons including their
  • Direct damage by feeding on crop plants in the field or by infesting stored products
  • Indirect damage by spreading viral diseases of crop plants especially by sucking insects such as leafhoppers
  • Spreading disease among humans and livestock
  • Annoyance to humans

Some types of pest insects are listed below.


Most lice are scavengers, feeding on skin and other debris found on the host's body, but some species feed on sebaceous secretions and blood. Most are found only on specific types of animals, and, in some cases, only to a particular part of the body. For example, in humans, different species of louse inhabit the scalp and pubic hair. Lice generally cannot survive for long if removed from their host.

A louse's egg is commonly called a nit. Many lice attach their eggs to their host's hair with specialized saliva. Living lice eggs tend to be pale white. Dead lice eggs are more yellow.

Humans host three different kinds of lice: head lice, body lice, and pubic lice.

A few effects of lice infestation upon the host
  • Direct damage by feeding on crop plants in the field or by infesting stored products
  • Indirect damage by spreading viral diseases of crop plants especially by sucking insects such as leafhoppers
  • Spreading disease among humans and livestock
  • Annoyance to humans

Bed Bugs

Bed bugs are parasitic insects of the cimicid family that feed exclusively on blood. Bed bugs are mainly active at night, but are not exclusively nocturnal. They usually feed on their hosts without being noticed.Bed bugs have been known as human parasites for thousands of years.

Adult bed bugs are light brown to reddish-brown, flattened, oval-shaped and have no hind wings. Adults grow to 4–5 mm in length and 1.5–3 mm wide.

Bed bugs are attracted to their hosts primarily by carbon dioxide, secondarily by warmth, and also by certain chemicals.

Bed bugs have six life stages, five immature nymph stages and a final sexually mature adult stage

Although under certain cool conditions adult bed bugs can live for as long as a year without feeding, under typically warm conditions they will try to feed at five to ten day intervals and adults can survive for about five months without food.


The mosquitoes are a family of small, midge-like flies: the Culicidae. Although a few species are harmless or even useful to humanity, most are a nuisance because they consume blood from living vertebrates, including humans. The females of many species of mosquitoes are blood-eating pests. In feeding on blood, some of them transmit extremely harmful human and livestock diseases, such as malaria, yellow fever and filariasis.

Like all flies, mosquitoes go through four stages in their life cycle: egg, larva, pupa, and adult. In most species, adult females lay their eggs in stagnant water; some lay eggs near the water's edge; others attach their eggs to aquatic plants.

Females of many common species of mosquito can lay 100–200 eggs during the course of the adult phase of their lifecycle.

Length of the adult varies, but is rarely greater than 16 mm and weight up to 2.5 milligrams.

Typically, both male and female mosquitoes feed on nectar and plant juices, but in many species the mouthparts of the females are adapted for piercing the skin of animal hosts and sucking their blood.


Termites are a group of eusocial insects. While termites are commonly known, especially in Australia, as "white ants", they are for practical purposes unrelated to the ants.

Termites mostly feed on dead plant material, generally in the form of wood, leaf litter, soil, or animal dung.

As eusocial insects, termites live in colonies that, at maturity, number from several hundred to several million individuals. A typical colony contains nymphs (semimature young), workers, soldiers, and reproductive individuals of both sexes, sometimes containing several egg-laying queens.

At maturity, a primary queen has a great capacity to lay eggs. In some species, the mature queen has a greatly distended abdomen and may produce 20000 to 30000 eggs a day. A termite queen can live for 45 years.
Termites are weak and relatively fragile insects that need to stay moist to survive. They can be overpowered by ants and other predators when exposed.



Locusts are the swarming phase of certain species of short-horned grasshoppers in the family Acrididae. These are species that can breed rapidly under suitable conditions and subsequently become gregarious and migratory when their populations become dense enough.

Locusts are nomadic and rapidly strip fields and greatly damage crops. The adults are powerful fliers; they can travel great distances, consuming practically all green material wherever the swarm settles.

Though the female and the male look alike, they can be distinguished by looking at the end of their abdomens. The male has a boat-shaped tip, while the female has two serrated valves that can be either apart or kept together.

Locusts are edible insects, and are considered a delicacy in some countries.



Weevil are usually small, less than 6 millimetres, and herbivorous. Many weevils are damaging to crops. The grain or wheat weevil damages stored grain. The boll weevil attacks cotton crops. It lays its eggs inside cotton bolls, and the young weevils eat their way out.

Weevils are often found in dry foods including nuts and seeds, cereal and grain products, such as pancake mix. In the domestic setting, they are most likely to be observed when a bag of flour is opened. Their presence is often indicated by the granules of the infested item sticking together in strings, as if caught in a cobweb.

Insects and Spiders

The facts about butterflies
The life-cycle of a butterfly
Difference between Butterflies & Moths
The facts about ants
The facts about bees
The facts about beetles
The facts about grasshoppers
The facts about pest insects
Interesting facts about insects
The facts about spiders

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